/* * Copyright (c) 2016, 2018, Red Hat, Inc. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /** * @test * @summary Logic that moves a null check in the expanded barrier may cause a memory access that doesn't depend on the barrier to bypass the null check * @requires vm.flavor == "server" * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:-TieredCompilation * -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC * -XX:+StressGCM -XX:+StressLCM TestExpandedWBLostNullCheckDep */ public class TestExpandedWBLostNullCheckDep { static void test(int i, int[] arr) { // arr.length depends on a null check for arr if (i < 0 || i >= arr.length) { } // The write barrier here also depends on the null check. The // null check is moved in the barrier to enable implicit null // checks. The null check must not be moved arr.length arr[i] = 0x42; } static public void main(String[] args) { int[] int_arr = new int[10]; for (int i = 0; i < 20000; i++) { test(0, int_arr); } try { test(0, null); } catch (NullPointerException npe) {} } }